"It was a disappointment, but I trust Ridley [Scott] and Emma [Watts] to know the right story when they find it. When universes are as rich as “Alien,” they can stay in a too familiar groove — in which case you’re in trouble — but they can also find a planet or a storyline or a villain that also lives in that universe that can be groundbreaking."

That's a new article, only about a week old. Here's a different Fox executive back in July:

While Ridley Scott has previously said he wants to shoot two more Alien movies, Alien Covenant struggled to sell enough tickets to ensure another instalment.

"It got great reviews and was everything we set out for it to be, it just didn't hit the note at the box office," says Fred Baron, the 20th Century Fox executive on the movie: "It will be a profitable film for the studio but whether there's another one [is uncertain]."